Fdi 6

CDI (CAT#, NO75-0015) was obtained from ChemDiv (San Diego, CA, USA). The dsDNA binding domain of FoxM1 (FoxM1-DBD) tagged with His×6 was supplied by Dr. Shin SJ (Yonsei University College of Medicine, Seoul, Korea). Streptavidin-XL-665 and anti-His×6 cryptate were purchased from Cisbio (Codolet, France). Biotinylated oligomers (sense: 5′-Biotin-TEG-AAA CAA ACA AAC AAT C-3′ and antisense: 5′-GAT TGT TTG TTT GTT T-3′) were obtained from Bioneer (Daejeon, South Korea). FDI-6, which was used as a reference, and all other reagents, including MgCl₂, EDTA, glycerol, DTT, NaCl, and Brij-35, were obtained from Sigma-Aldrich (St. Louis, MO, USA).

The cells were seeded in 96-well culture plates as 5000 cells/well in 100 µL completed DMEM media, and were incubated at 37 °C overnight before adding FDI-6 (SML1392, Sigma Aldrich, Singapore) in varied concentrations. After being incubated further for 3 days, the cells were washed with PBS, fixed with 10% trichloroacetic acid for 1 h, and then washed again with PBS. Then, 1% SRB solution was added to the 50 µL/wells for staining. The samples were incubated for 30 min at room temperature and rinsed three times with 1% acetic acid afterward. The culture plates were dried at room temperature overnight. The stained samples were dissolved in 50 µL of 10 mM Tris base solution and the absorbance was measured at 560 nm. The inhibitory concentration 50% (IC₅₀) was determined by using the IC₅₀ calculator tool of the AAT Bioquest webpage [55 ].